1. Field of the Invention
This invention is directed to air cleaner assemblies incorporated into forced air HVAC systems.
2. Related Art
Air cleaner assemblies for forced air heating, cooling and ventilation (HVAC) systems have been used for decades. Such air filtration devices and structures vary widely from simple panel filters to two substantially different types of air cleaners: electronic air cleaners and extended surface pleated mechanical media filters. Extended surface filters can be supplied in a collapsible configuration or in a cartridge configuration. Within the broad class of media filters, there is a wide range of filter media and structures. At one end of the conventional range of media filters are the relatively low-efficiency fiberglass or spun glass panel filters. These filters use a weave or felt of glass fibers to trap airborne particulates and the like. Typically, such fiberglass mat filters have an American Society of Heating Air Conditioning and Refrigeration Engineers (ASHRAE) average Arrestance of 50-60%, per Standard 52.1. Such filters are typically one or two inches thick. Pleated media filters are a step up from basic fiberglass mat filters. Such pleated media filters are typically thin synthetic or glass fiber sheets and typically have ASHRAE MERV ratings from 6-16, per Standard 52.2.
HVAC systems can use in-duct air cleaners. Such in-duct air cleaners include a frame or filter housing that connects to the inflow and/or outflow portions of the duct work and an opening that allows a filter to be inserted and removed from the air cleaner. Typically, the in-duct air cleaner is designed for a specific type and size of filter. The in-duct air cleaner typically includes a door or other panel that closes the opening of the filter housing through which the filter is inserted and removed from the in-duct air cleaner.